Biomass based small scale combined heat and power technologies

At present governments aim to increase the share of renewable energy in the European Union as an attempt to reduce the emissions of green house gases. One approach is to replace some of the non-renewable power generation methods, with biomass based combined heat and power generation technologies. The main objective of this study has been to investigate the state-of-the- art in the area of small-scale biomass based combined heat and power generation. Other aims have been to identify proper biomass based CHP technologies for the county of Norrbotten and to make a pre-study of such a plant located in the small community Harads. The technologies investigated were the Organic Rankine Cycle (ORC), steam engine, gas engine and externally fired gas turbine (EFGT). An economic comparison shows that no one of the considered technologies is economically viable at present Swedish electric prices and green electric certificates. In order to reach profitability the green electricity certificates or the electricity prices must increase with at least 35 €/MWhel. Still if the problem of fouling and corrosion in the externally fired gas turbines heat exchanger is solved in a sufficient way, this technology shows potential for the future due the high electrical efficiency and resulting low cost of electricity. This is also true for the gas engine, which has similar problems with the dirty gas, yet this technology might be more suitable in power ranges higher than 5 MWth. Regarding the Harads plant, a 2 MWth Organic Rankine Cycle was assessed to be the most suitable technology. Still, calculations showed that the electricity share will be unprofitable, but the full-plant will be economically viable due to a high return from the heat sales. Furthermore a sensitivity analysis showed that the most important parameter for the cost of electricity is the annual operation hours in addition it also showed the fuel price has not so much influence on the cost of electricity.Validerat; 20101217 (root